IFNG and early-onset autosomal dominant Alzheimer disease: Controversially, there are also some studies showing that IFNγ can increase proliferation of neural precursor cells,12 or enhance neurogenesis in an Alzheimer's disease mouse model.20 In fact, it is known that IFNγ can have opposing effects on inhibiting or promoting proliferation depending on the molecular pathways activated.21 For instance, it has been shown that the increase on neural precursor cells' proliferation mediated through the sonic hedgehog pathway is dysfunctional in these mice leading to the differentiation of aberrant cells.11